Selection of maize top-crosses for different nitrogen levels through specific combining ability

ABSTRACT An alternative to increase yield without raising the production costs and minimizing the dependence of agricultural inputs is the development of maize genotypes presenting high nitrogen (N) use efficiency under low N level conditions. Thus, the objective of this study was to estimate the specific combining ability of maize top-crosses under high and low nitrogen (N) conditions and to select high-yielding hybrids for both conditions. The grain yield of 110 top-cross hybrids was evaluated in 2012 in two locations in the Brazilian Midwest. Partial diallel analysis was performed with the adjusted means of each of the individual top-cross analyses. Specific combining ability (SCA) of the hybrids and their interaction with N levels was estimated for each location. The mean grain yield of the 11 hybrids selected by the highest SCA estimates for high and low N was higher than the controls mean in approximately 330 and 241 kg∙ha-1. These results demonstrate that the selection for each environment was efficient and reveals the possibility of developing new hybrids for the Brazilian Cerrado region.